This invention in general relates to electronic circuits mounted on metallic substrates and, more particularly, to a method and apparatus for securing an electrically conductive interconnect through the metallic substrate.
Engine mounted electronic control modules for vehicular engines are subject to a high level of heat and vibration. In these applications, electronic components and circuits are formed on a metallic substrate that typically needs to be enclosed within a sealed metallic housing. In the past, it has been difficult and costly to electrically connect the internally enclosed electronic components and circuits to external devices.
Providing a through-hole to electrically connect circuits has been used on ceramic and fiberglass substrates or boards. However, these schemes do not address electronic devices that have thermally conductive metallic substrates such as aluminum. When using a metallic substrate and within a metallic housing, care must be taken so as to electrically insulate any components and connectors from the metallic substrate and housing.
For metallic substrates, prior methods have extended a plurality of pins through a single window opening in the metallic substrate. An insert-molded lead frame extends through the window opening and provides isolation between the plurality of pins. A series of wire bonds are then necessary to connect the pins to the electronic circuit on the metallic substrate. Moreover, a separate special plating process is typically required on the metallic substrate for the circuits and components. The use of wire bonds and plating process, however, increases the complexity of the manufacturing process and, accordingly, increases the cost of the module.
An interconnect within a through-hole has been used for steel substrates on voltage regulators. The through-hole in that application, however, is glass sealed and still requires the use of wire bonds to connect the interconnect to the circuit on the metallic substrate.
In sum, current devices and methods to connect electronic components and circuits through a metallic substrate are costly. Accordingly, there is a need for improved ways to provide an interconnect approach that reduces the complexity of the manufacturing process and reduces costs. This is especially important in high volume applications such as electronic control modules for vehicles. Moreover, new interconnect approaches should take advantage of lower cost metallic substrates such as aluminum.
It is, therefore, desirable to provide an improved device and method of securing an electrically conductive interconnect through a metallic substrate to overcome most, if not all, of the preceding problems.